1. Field of the Invention
This invention relates to thermal recording head for use in a recording system utilizing a thermal energy for recording.
2. Related Background Art
The recording system utilizing thermal energy for recording has been characterized by very low noise at the recording due to the non-impacting mechanism and has been gradually regarded as important because of the possibility of colorization.
In such a recording system, recording information is transmitted to a thermal recording head, that is, an electro-thermal conversion device, in the form of an electric signal. The electro-thermal conversion device for this purpose comprising a substrate, a heating resistor layer formed thereon, and at least one pair of electrodes connected to the heating resistor layer, where the substrate means that which can support the heating resistor layer, and can comprise a support and, if required, a layer formed thereon. Generally, the thermal recording head is in a relatively small form, and thus the heating resistor layer can be in a thin film form, or in a thick film form or in a semi-conductor form. Particularly, the thin film form is preferable as a constituent member of the thermal recording head because of its less consumption of electric power than that of other forms, and also owing to a relatively good heat response, and thus its application has been increasing.
The properties required for the heating resistor layer of a thermal recording head are good heating response to a predetermined electric signal, good heat conductivity, good heat resistance to its own heat generation, an good durabilities, for example, durability against thermal hysteresis, etc. When a thermal recording head is used through a pressing contact with a heat-sensitive paper or a heat transfer ink ribbon, a small coefficient of friction on the recording medium is further required.
However, the heating resistor layers of thermal recording heads so far used have not always satisfied the required properties and further improvement in the properties has been still desired.
To improve the wearing resistance of thermal recording heads, a wearing-resistant layer has been provided on the surface of the heating resistor layer at the sacrifice of the heat response.
When recording is made in a complete dot form on a recording medium such as paper with a rough surface, etc. by means of the conventional thermal recording head, it is necessary to more strongly press the thermal recording head onto the recording medium, resulting in an accelerated wearing. Thus, further improvement in the properties has been desired.